Structural delineation and phase-dependent activation of the costimulatory CD27:CD70 complex

Area of Science:

• Immunology
• Structural Biology
• Molecular Medicine

Background:

• CD27 is a crucial costimulatory receptor for lymphocytes, enhancing antitumor and anti-infection immunity.
• CD70, its ligand, is frequently overexpressed on tumor cells, making it a promising therapeutic target.
• The precise molecular interactions between CD27 and CD70 have remained unclear.

Purpose of the Study:

• To determine the atomic details of the human CD27-CD70 complex structure.
• To identify key residues governing the CD27-CD70 interaction.
• To investigate the functional impact of CD70 presentation on T-cell stimulation.

Main Methods:

• X-ray crystallography was used to obtain the structure of the human CD27-CD70 complex.
• Rational mutagenesis and analysis of disease-correlated mutations were employed to map interaction sites.
• In vitro functional assays assessed T-cell stimulation by different CD70 constructs.

Main Results:

• The crystal structure revealed a 3:3 homotrimeric assembly of CD70 engaging CD27 receptors.
• Key amino acid residues critical for the CD27-CD70 interaction were identified.
• Plate-bound CD70 constructs demonstrated enhanced potency in stimulating T-cells compared to soluble forms.

Conclusions:

• The study provides unprecedented atomic-level insight into the CD27-CD70 costimulatory interaction.
• This structural and functional understanding can guide the development of novel CD70-targeted cancer immunotherapies.
• Optimizing CD70 presentation may enhance its efficacy in therapeutic applications.